JP2016504238A - Tire overlay composition - Google Patents

Abstract

A tire comprising an overlay ply, wherein (i) the shoulder portion of the overlay comprises an elastomer and polymeric or non-polymeric reinforcing short fibers present in an amount of 0.1 to 10 parts of fiber per 100 parts of elastomer; The short fibers have a tenacity of at least 2 g / dtex, a modulus of at least 10 g / dtex and a length of 0.1-8 mm, and the fibers are substantially parallel to each other with a controlled orientation angle in the overlay. And the orientation is selected such that it will reduce tire noise, and (ii) the portion of the overlay in the crown of the tire is a continuous filament polymer fiber or a continuous metal strand or combinations thereof The cord includes a circumferential direction around the tire We are not aligned, tire.

Description

  The present invention relates to a tire overlay composition that reduces tire noise.

  There continues to be a need for improved passenger car and truck tire performance. Important performance attributes include noise, maneuverability, wear resistance, rolling resistance, and ride comfort. As tire companies strive to reduce the noise emitted from automobile and truck tires, the reduction of tire noise is becoming the focus of the industry. For example, the European Union is developing legislation to significantly reduce the passing noise from tires.

  Certain fibers have been utilized in high performance tire manufacturing. US 2002/0069948 teaches the use of short fibers at an angle generally perpendicular to the tire surface. The purpose of these configurations is said to be improved maneuverability and / or acceleration. US 2007/0221303 utilizes short fibers in a configuration that increases the directional stiffness of the tread. These fibers are said to be aligned slightly perpendicular to the circumferential direction of the tread length. U.S. Pat. No. 4,871,004 discloses an aramid reinforced elastomer in which short, discontinuous fibrillated aramid fibers are dispersed in rubber. The arrangement disclosed in this patent is said to maximize lateral (axial or circumferential) stiffness and modulus. However, these arrangements are not taught to be beneficial for noise reduction.

  US 2010/0236695 relates to a tire having a composite tread block comprising a cured elastomer and 0.1 to 10 parts of fiber per 100 parts by weight of elastomer, the fiber being at least 6 grams of tenacity per dtex. And having a modulus of at least 200 grams per dtex. The major portion of the fibers is oriented in a direction that will reduce the noise generated by the tire tread in contact with the road surface.

The present invention is a tire including an overlay ply,
(I) The shoulder portion of the overlay comprises an elastomer and a polymeric or non-polymeric reinforcing short fiber present in an amount of 0.1 to 10 parts of fiber per 100 parts of elastomer, wherein the short fiber is at least 2 per dtex. Tensity of grams, a modulus of at least 10 grams per dtex, and a length of 0.1-8 mm, and the fibers are aligned substantially parallel to each other at a controlled orientation angle in the overlay, the orientation Is selected such that it will reduce tire noise, and (ii) the portion of the overlay in the crown of the tire includes cords of continuous filament polymer fibers or continuous metal strands or combinations thereof, Are circumferentially aligned around the tire
Regarding tires.

The present invention further includes a tire including an overlay,
(I) The overlay in the crown portion of the tire comprises an elastomer and a polymeric or non-polymeric reinforcing short fiber present in an amount of 0.1 to 10 parts of fiber per 100 parts of elastomer, the short fiber being 1 dtex. Having a tenacity of at least 2 grams per d, a modulus of at least 10 grams per dtex and a length of 0.1-8 mm, and the fibers are aligned substantially parallel to each other in a controlled orientation angle within the overlay The orientation is selected such that it will reduce tire noise, and (ii) the shoulder portion of the tire overlay comprises cords of continuous filament polymer fibers or continuous metal strands or combinations thereof, The cord is aligned circumferentially around the tire It is,
Regarding tires.

The tire coordinate system is depicted. It is tire sectional drawing. It is a part of tire sectional view of an overlay field which shows a 1st embodiment of the present invention. It is a part of tire sectional view of an overlay field which shows a 2nd embodiment of the present invention. It is a part of tire sectional view of an overlay field which shows a 3rd embodiment of the present invention. FIG. 4 depicts a tire cross-sectional view of an overlay region of a tire showing a third embodiment of the present invention. The orientation of the plane in the general direction is depicted. The orientation of the plane in two directions is depicted.

  Vehicle tire noise comes from many sources. FIG. 1 is useful in explaining how this noise is generated and for defining the direction used herein. FIG. 1 generally shows a tire having a tread block 11 as 10 and also shows the main coordinate axes for this tire. The circumferential direction is the traveling direction, ie X. The meridian direction is indicated as Y and the radial direction is indicated as Z. The meridian direction is sometimes referred to as the axial or lateral direction. For clarity, the road surface is in the XY plane. The tire also uses a component called a sub-tread that provides support to the tread block 11 just below the tread. The sub-tread is between the tread block and a first reinforcing layer that is either an overlay (also called a cap ply), belt or breaker.

  In FIG. 2, generally indicated as 20 is a tire cross section including two main portions, a sidewall portion 21 and a crown portion 22. The tire sidewall is an area from the tire bead 23 to the tread 29. “Crown” means a tire portion within the tire tread width limit. The tire shoulders 21a and 21b are the upper portions of the sidewalls directly below the tread ends. The bead 23 is installed where the tire is located on the rim flange. The bead consists of a high-strength steel wire made into a non-stretchable annulus. The bead serves to secure the ply and hold the assembly on the rim of the wheel. The shape or contour of the bead matches the flange of the wheel to prevent the tire from swinging or sliding on the rim. The carcass cord 24 imparts strength and load resistance to the tire. “Carcass” means a tire structure that excludes belt structures on the ply, tread, undertread, and sidewall rubber, but includes beads. Carcass is sometimes called a case. The carcass cords are fixed by winding them around the bead wire 23. FIG. 2 also shows the wheel rim 25. “Tread” means the portion of the tire that comes into contact with the road when the tire is normally inflated and under normal load. A “belt” is a narrow layer of tire cord material just below the tread in the tire crown. In truck tires, the belt is commonly called a breaker. The overlay 26 is a reinforcing layer installed between the outward surface of the tire steel belt 18 and the bottom of the tire tread 29. Conventional overlays include continuous filament cords that extend in the circumferential direction of the tire.

A first embodiment of the present invention is a tire including an overlay,
(I) The shoulder portion of the overlay comprises an elastomer and reinforcing polymer staple fibers present in an amount of 0.1 to 10 parts fiber per 100 parts elastomer, wherein the staple fibers are at least 2 grams tenacity per dtex; Having a modulus of at least 10 grams per dtex and a length of 0.1-8 mm, and the fibers are aligned substantially parallel to each other at a controlled orientation angle in the overlay, the orientation being Selected to reduce tire tread noise, and (ii) the tire overlay portion in the crown includes cords of continuous filament polymer fibers or continuous metal strands or combinations thereof, the cords surrounding the tire Are aligned in the circumferential direction,
Tire.

  FIG. 3 depicts this first embodiment, generally designated 30 as the tire portion including the carcass 24 and belt 18. There is an overlay on the belt. In the tire shoulder region 21a, the overlay includes elastomer and reinforcing polymer short fibers 31. In the crown region, the overlay includes cords 32 of continuous filament polymer fibers or continuous metal strands or combinations thereof. Note that the short fibers are shown as being oriented in the meridian direction purely for illustrative purposes.

A second embodiment of the present invention is a tire including an overlay,
(I) the tire crown partial overlay comprises an elastomer and reinforcing polymeric staple fibers present in an amount of 0.1 to 8 parts fiber per 100 parts elastomer, wherein the staple fibers are at least 2 grams tenacity per dtex; Having a modulus of at least 10 grams per dtex and a length of 0.1-8 mm, and the fibers are aligned substantially parallel to each other at a controlled orientation angle in the overlay, the orientation being And (ii) the tire overlay shoulder portion includes cords of continuous filament polymer fibers or continuous metal strands or combinations thereof, the cords being circular around the tire Aligned in the circumferential direction,
Tire.

  FIG. 4 depicts a second embodiment, generally designated as 40 by the tire portion including the carcass 24 and the belt 18. There is an overlay on the belt. In the tire shoulder region 21a, the overlay includes cords 32 of continuous filament polymer fibers or continuous metal strands or combinations thereof. In the tire crown region, the overlay includes elastomers and reinforcing polymer staples 31.

  FIG. 5 depicts a third embodiment of the present invention, generally designated as 50, the tire portion including the overlay. In the overlay, both the overlay shoulder portion 21a and the overlay crown portion include a mixture of elastomer and reinforcing polymeric staple fibers 31 and cords 32 of continuous filament polymer fibers or continuous metal strands or combinations thereof.

  FIG. 6 depicts a fourth embodiment of the present invention, generally indicated as a tire cross section at 60. One half of the overlay, the first half (H1), includes a shoulder portion 21aa and a crown portion 63aa. The first half of the overlay further includes elastomeric and reinforcing polymer staples 31. The other half of the overlay, the second half (H2), includes a shoulder portion 21ab and a crown portion 63ab. The second half of the overlay further includes continuous filament polymer fibers or continuous metal strands or combinations 32 thereof. The positions of H1 and H2 are interchangeable with respect to whether they are inside or outside the tire when installed in a vehicle.

  In yet another embodiment, the tire overlay ply includes an elastomer and a polymeric or non-polymeric reinforcing short fiber present in an amount of 0.1 to 10 parts of fiber per 100 parts of elastomer, wherein the short fiber is 1 dtex. Having a tenacity of at least 2 grams per d, a modulus of at least 10 grams per dtex and a length of 0.1-8 mm, and the fibers are aligned substantially parallel to each other at a controlled orientation angle in the overlay; The orientation is selected so that it will reduce tire noise. There are no continuous filament polymer fibers or continuous metal strands in the overlay.

  The elastomeric part comprising short fibers or continuous fibers can be formed from one part or from a plurality of parts positioned adjacent to each other either across the width of the part or through the thickness of the part.

Short fibers Short fibers in the elastomer constitute one component of the overlay. By careful selection of the short fiber orientation and planar arrangement of the layers in the overlay containing short fibers, it is possible to customize the overlay design to address specific noise reduction challenges. In some tire configurations, the fibers are substantially aligned in the meridian direction within the overlay. In certain tires, the short fibers are substantially aligned with one another substantially circumferentially. In certain tires, the short fibers are substantially aligned with one another in a substantially radial direction. By substantially is meant that more than 50% of the short fibers in the layer are oriented in one direction. More preferably, more than 70% of the short fibers in the layer are oriented in one direction. Most preferably, more than 85% of the short fibers in the layer are oriented in one direction. Aligned or oriented means that the fibers are arranged such that the long dimension of the fibers will be oriented in the alignment direction. This fiber alignment imparts anisotropic mechanical stiffness properties to the tire overlay region containing short fibers. In some embodiments, the length of the short fiber is 0.1-8 mm, and in other embodiments it is 0.1-3 mm.

  Overlay layers containing aligned fibers can also be oriented in different planar configurations. For example, FIG. 7 depicts the XY planar orientation of the overlay layer. These layers are fibers oriented in the meridian direction (Y), fibers oriented in the circumferential direction (X), or alternately between meridian (Y) and circumferential (X) orientations. It could contain fibers arranged to repeat. The fiber orientation may also be different for different portions of the overlay layer having different planar orientations as depicted in FIG. 8, and in particular may include two reinforcement directions. For example, in the XZ plane, the fibers could be circumferential (X) or radial (Z), whereas in the XY plane, the fibers are circumferential (X) or meridian (Y) You will get. In the YZ plane (not shown), the fibers could be in the meridian direction (Y) or radial direction (Z). For example, meridian and circumferentially oriented fibers in the overlay and fibers oriented radially in the overlay have been found to be very effective in reducing noise. On the other hand, orienting the fibers circumferentially within the overlay can be most easily accomplished, but may provide a smaller relative benefit in noise reduction. There are many possible fiber orientations in the overlay structure between these two situations. For example, with further reference to FIG. 8, fibers in the XZ plane of the overlay could be oriented at some angle between the circumferential direction (X) and the radial direction (Z). Similarly, the fibers in the XY plane of the overlay could be oriented at some angle between the circumferential direction (X) and the meridian direction (Y). Appropriate selection of machinery and manufacturing systems, including extrusion dies, will result in the desired fiber orientation in each subtread extrusion profile.

  The fiber orientation in the layers in the XY, YZ, or XZ plane is preferably orthogonal, but the fibers are also angled between 5 and 85 degrees with respect to either the circumferential, meridian or radial direction. Can be aligned without being orthogonal. More preferably, the fibers are aligned at an angle between 15 and 70 degrees. Such bias angle orientation can be achieved by rolling the elastomer sheet in two directions.

  Another aspect of the invention relates to a method for making a composite overlay as described herein, the method comprising rolling one or more layers by rolling or extruding a mixture of elastomer and reinforcing fibers. The manufacturing process is included. In some embodiments, the method further comprises integrating multiple layers.

  Thus, the present invention in which there is a controlled orientation of fibers in the elastomer is different from rubber compounds reinforced with carbon black or other particulates that exhibit random or isotropic reinforcement. Short fiber reinforcement is added using short fibers, floc or pulp. In some embodiments, the higher the short fiber or pulp modulus, the better the resulting performance. Thus, high modulus fibers such as aramid fibers and pulp can be advantageously placed in the plane of the overlay. However, it should be noted that in addition to aramid, any short fiber or pulp that increases the meridian overlay stiffness will function to some extent. Exemplary short fibers include those made from polymers such as aromatic polyamides, aromatic copolyamides, aliphatic polyamides, polyesters, polyolefins, polyazoles, and mixtures thereof. Such fibers may be used directly during fiber compounding, or may be added as a premix or masterbatch in which the fibers are pre-blended with a portion of the elastomer to form a concentrate.

  The tire overlay of the present invention comprises a cured elastomer having 0.1 to 10 parts (phr) of short fibers, flocks, or pulp per 100 parts by weight of elastomer. In some embodiments, the short fiber content is 1-8 phr or even 2-6 phr. The fiber has a tenacity of at least 2 grams per dtex and a modulus of at least 10 grams per dtex. In some embodiments, the fiber has a tenacity of 500-1100 grams per dtex. Short fibers can be made from continuous fibers to form floc, pulp, and other chopped fiber forms, and as described herein, any of these forms, unless stated otherwise It can be regarded as a fiber. Some fibers have a length to diameter ratio of 5 to 10,000, more preferably 10 to 5000. As described herein with respect to the present invention, staple fibers having a diameter of less than 15 micrometers include pulp and fibers known as floc. Flock is made by cutting continuous fibers to a short length of about 0.1 to 8 millimeters, more preferably about 0.1 to 6 millimeters. The production of such fibers is well known to those skilled in the art. Some of these fibers, including those coated with adhesion promoters, are commercially available.

  Some fibers used in the present invention are in the form of pulp. Pulp contains fibrillated fibers, sometimes made by chopping longer fibers. Aramid pulp can be made, for example, by refining aramid fibers, and in some embodiments has a length distribution up to about 8 millimeters with an average length of about 0.1 to 4 millimeters. Commercially available aramid pulp includes E.I. I. Kevlar (R) pulp from du Pont de Nemours and Company, Wilmington DE, (DuPont), and Teijin (TM) Twaron (R) pulp. Another form of pulp known as micropulp can be produced according to US 2003/0114641. Short fibers can also be of metal or ceramic.

The shoulder portion and / or crown portion of the cord overlay also contains the cord as the second component of the overlay structure. The cord can include continuous polymer filaments, metal wire strands, or both. As used herein, a “filament” is a relatively soft, macroscopically uniform object having a length and a width across the cross-sectional area of the object perpendicular to the length of the object. Means an object with a high ratio. In this specification, the term “fiber” is used interchangeably with the term “filament”. The cord can be a single polymer filament or wire strand or a plurality of polymer filaments or wire strands. In some embodiments, two or more cords can be twisted together to form a merge cord. The merge code is sometimes referred to as a cable code or a hybrid code. Examples of merge codes are US Pat. Nos. 5,551,498; 4,176,705; 4,807,680; and 4,878,343. As well as U.S. Patent Application Publication No. 2009/0159171. The cord is arranged circumferentially around the tire.

  A preferred metal wire is steel. Typical steel compositions have a carbon content of 0.60% to 1.1%, a manganese content in the range of 0.20 to 0.90% and a silicon content in the range of 0.10 to 0.90%. including. Other elements (eg, sulfur, phosphorus, chromium, boron, cobalt, nickel and vanadium) may each be present at levels below 0.5%.

  The steel wire may have a cross section that includes one or more axes of symmetry. For example, an elliptical or rectangular cross section has two symmetry axes, and a triangular cross section has three symmetry axes. In preferred embodiments, the steel wire cross-section is circular or substantially circular.

  In some embodiments, the major cross-sectional dimension of the wire is in the range of 0.04 mm to 1.1 mm, more preferably 0.07 mm to 0.60 mm. This dimension is the diameter in the case of a circular cross section. The wire is typically provided with a coating that provides an affinity for rubber. Such coatings include those that can react with sulfur atoms in the rubber (eg, copper, zinc and alloys of such metals (eg, brass)). In a preferred embodiment, zinc is used as the coating substrate when the polyamide yarn constitutes the outer surface of the hybrid cord, and brass is the preferred coating material otherwise.

  Elastomeric components including short fibers or continuous fibers can be formed from one part or from multiple parts positioned adjacent to each other.

Fiber Polymers The polymeric material used in the elastomer component short fibers and cord component continuous filaments can be made from any polymer that results in high strength fibers. Suitable polymeric materials are aromatic polyamides, aromatic copolyamides, aliphatic polyamides, polyesters, polyolefins, polyazoles, and mixtures thereof. Suitable non-polymeric materials are glass fibers, carbon fibers and cellulosic fibers. Some fibers may be in the form of nanotubes. Both single-walled and multi-walled nanotubes are suitable. A preferred aromatic polyamide is para-aramid. When the polymer is a polyamide, aramid is preferred in some embodiments. The term “aramid” refers to a polyamide in which at least 85% of the amide (—CONH—) bonds are directly linked to two aromatic rings. Suitable aramid fibers include Twaron (R), Sulfron (R), Technologya (R), Kolon Industries Inc., all available from Teijin Aramid. Heracon (TM) from or Kevlar (R) available from DuPont. Aramid fibers are available from Man-Made Fibers-Science and Technology, Volume 2, Section titrated Fiber-Forming Aromatic Polymers, page 297, W. et al. Black et al. , Interscience Publishers, 1968. Aramid fibers and their production are described in U.S. Pat. Nos. 3,767,756; 4,172,938; 3,869,429; 3,869,430. Also disclosed in US Pat. No. 3,819,587; US Pat. No. 3,673,143; US Pat. No. 3,354,127; and US Pat. No. 3,094,511. Has been.

  In some embodiments, the preferred aramid is para-aramid. One preferred para-aramid is poly (p-phenylene terephthalamide) called PPD-T. PPD-T means a homopolymer resulting from a mole-for-mole polymerization of p-phenylenediamine and terephthaloyl chloride, and in addition to p-phenylenediamine, a small amount of other diamines. And copolymers resulting from incorporating small amounts of other diacid chlorides with terephthaloyl chloride. As a general rule, other diamines and other diacid chlorides can only be prepared using p-phenylenediamine or terephthalodies, provided that the other diamines and diacid chlorides do not have any reactive groups that interfere with the polymerization reaction. It can be used in amounts up to about 10 mole percent of yl chloride, or perhaps slightly more. PPD-T also incorporates other aromatic diamines and other aromatic diacid chlorides such as 2,6-naphthaloyl chloride or chloro or dichloroterephthaloyl chloride or 3,4'-diaminodiphenyl ether. Also means the resulting copolymer.

  It has been found that additives can be used with aramids and up to as much as 10% by weight or more of other polymeric materials can be blended with aramids. Copolymers having about 10 percent or more other diamines instead of aramid diamines, or copolymers having about 10 percent or more other diacid chlorides instead of aramid diacid chlorides can be used.

  When the polymer is a polyolefin, polyethylene or polypropylene is preferred in some embodiments. Polyolefin fibers are used only when the processing temperature required to compound the fiber and elastomer, to roll or extrude the compound, or to cure the compound in the tire assembly is below the melting point of the polyolefin Can be done. The term “polyethylene” means a predominantly linear polyethylene material, preferably having a molecular weight greater than 1 million, wherein the polyethylene material comprises a small amount of chain branches or no more than 5 modified units per 100 main chain carbon atoms. It may also contain comonomers, and may also contain up to about 50 weight percent of one or more polymer additives (eg, alkene-1-polymers, particularly low density polyethylene, propylene, etc.) or low molecular weight additives (eg, common Antioxidants, lubricants, UV blockers, colorants, etc.) incorporated into the polyethylene material. Such polyethylene is commonly known as extended chain polyethylene (ECPE) or ultra high molecular weight polyethylene (UHMWPE). The preparation of polyethylene fibers is described in U.S. Pat. Nos. 4,478,083, 4,228,118, 4,276,348 and 4,344,908. It is handled by. High molecular weight linear polyolefin fibers are commercially available. The preparation of polyolefin fibers is addressed in US Pat. No. 4,457,985.

  In some preferred embodiments, the polyazole is a polyareneazole (eg, polybenzazole and polypyridazole). Suitable polyazoles include homopolymers and also copolymers. Additives can be used with the polyazole, and up to as much as 10% by weight of other polymeric materials can be blended with the polyazole. Copolymers having as much as 10 percent or more other monomers instead of polyazole monomers may also be used. Suitable polyazole homopolymers and copolymers are known procedures (eg, US Pat. Nos. 4,533,693, 4,703,103, 5,089,591). , 4,772,678, 4,847,350, and 5,276,128, or procedures derived therefrom). Can be done.

  Preferred polybenzazoles include polybenzimidazole, polybenzothiazole, and polybenzoxazole, and more preferably polymers that can form fibers having a yarn tenacity of 30 grams per denier (gpd) or more. In some embodiments, when the polybenzazole is polybenzothioazole, preferably it is poly (p-phenylenebenzobisthiazole). In some embodiments, when the polybenzazole is polybenzoxazole, preferably it is poly (p-phenylenebenzobisoxazole), more preferably poly (p-phenylene-2,6-benzobis) called PBO. Oxazole).

  Preferred polypyridazoles include polypyridoimidazole, polypyridothiazole, and polypyridooxazole, more preferably polymers that can form fibers having a thread tenacity of 30 gpd or more. In some embodiments, the preferred polypyridazole is polypyridobisazole. One preferred poly (pyridobisazolole) is a poly (1,4- (2,5-dihydroxy) phenylene-2,6-pyrido [2,3-d: 5] called PIPD. , 6-d '] bisimidazoles Suitable polypyridazoles (including polypyridobisazoles) are described in known procedures (eg, as described in US Pat. No. 5,674,969). Procedure).

  As used herein, the term “polyester” is intended to encompass a polymer in which at least 85% of the repeating units are a condensate of a dicarboxylic acid and a dihydroxy alcohol in which a bond is formed by formation of an ester unit. Is done. This includes aromatic, aliphatic, saturated, and unsaturated diacids and dialcohols. As used herein, the term “polyester” also encompasses copolymers (eg, block, graft, random and alternating copolymers), blends, and modifications thereof. In some embodiments, preferred polyesters include poly (ethylene terephthalate), poly (ethylene naphthalate), and liquid crystalline polyester. Poly (ethylene terephthalate) (PET) can include various comonomers including diethylene glycol, cyclohexanedimethanol, poly (ethylene glycol), glutaric acid, azelaic acid, sebacic acid, isophthalic acid, and the like. In addition to these comonomers, branching agents such as trimesic acid, pyromellitic acid, trimethylolpropane and trimethyloethane, and pentaerythritol can be used. Poly (ethylene terephthalate) can be obtained from any of terephthalic acid or its lower alkyl esters (eg, dimethyl terephthalate) and ethylene glycol or blends or mixtures thereof by known polymerization techniques. Another potentially useful polyester is poly (ethylene naphthalate) (PEN). PEN can be obtained from 2,6 naphthalenedicarboxylic acid and ethylene glycol by known polymerization techniques.

  Liquid crystalline polyesters can also be used in the present invention. As used herein, “liquid crystal polyester (LCP)” was tested using the TOT test or any reasonable variation thereof as described in US Pat. No. 4,118,372. In this case, it means a polyester that is anisotropic. One preferred form of liquid crystalline polyester is “totally aromatic”, ie, all groups in the polymer backbone (except for linking groups such as ester groups) are aromatic but are not aromatic. Can exist.

E-glass is a commercially available low alkali glass. One typical composition is 54% by weight SiO ₂ , 14% by weight Al ₂ O ₃ , 22% by weight CaO / MgO, 10% by weight B ₂ O ₃ and less than 2% by weight Na ₂ O / It consists of K ₂ O. Some other materials may also be present at the impurity level.

  S-glass is a commercially available magnesia-alumina-silicate glass. This composition is stiffer, stronger and more expensive than E-glass and is commonly used in polymer matrix composites.

  Carbon fibers are commercially available and are well known to those skilled in the art. In some embodiments, these fibers have a diameter of about 0.005-0.010 mm and consist primarily of carbon atoms.

  Cellulosic fibers can be made by spinning a liquid crystal solution of cellulose esters (formate and acetate) and then saponifying to produce regenerated cellulosic fibers.

Elastomer As used herein, the terms “rubber” and “elastomer” may be used interchangeably unless otherwise specified. The terms “rubber composition”, “compound rubber” and “rubber blend” may be used interchangeably to refer to “rubber blended or mixed with various ingredients and materials”, such terms being Well known to those skilled in the art of rubber mixing or rubber compounding. The terms “cured” and “vulcanized” can be used interchangeably unless otherwise specified. In the description of the present invention, the term “phr” refers to the number of parts of each material per 100 parts by weight of rubber (ie, elastomer).

  The elastomers of the present invention include both natural rubber, synthetic natural rubber and synthetic rubber. Synthetic rubber formulations can be any that are dissolved by common organic solvents, among others, polychloroprene and sulfur modified chloroprene, hydrocarbon rubber, butadiene-acrylonitrile copolymer, styrene butadiene rubber, chlorosulfone. There may be mentioned fluorinated polyethylene, fluoroelastomer, polybutadiene rubber, polyisoprene rubber, butyl and halobutyl rubber. Natural rubber, styrene butadiene rubber, polyisoprene rubber and polybutadiene rubber are preferred. A mixture of rubbers may also be utilized.

In some embodiments, the present invention relates to a method for manufacturing a composite overlay as described herein, the method comprising rolling or extruding a mixture of elastomer and reinforcing short fibers. A step of manufacturing one or more layers is included as one step. The method may further comprise the step of integrating a plurality of layers of short fibers in the elastomer. Different layers may or may not have the same fiber orientation. Methods for rolling, extruding and integrating such composite layers are well known to those skilled in the art and are described below. The overlay can be formed by means well known to those skilled in the art.

  Fiber alignment can be achieved by several well-known methods. One method involves high shear mixing of raw materials (polymers, fibers, and other additives) to compound the elastomer, followed by roll milling and / or rolling. High shear mixing ensures that the fibers and other additives are uniformly dispersed in the elastomer. At this stage, the fibers within the elastomer are randomly oriented. The first stage of the compounding process involves polymer mastication or degradation. Natural rubber can be broken down in an open kneading roll, but the more common practice is to use a high shear mixer (eg, a Banbury or Shaw mixer) with counter rotating blades. In some cases, a separate preliminary mastication step can be used. For synthetic rubbers, preliminary mastication is necessary only if the formulation contains a polymer blend. This is followed by masterbatching when most of the ingredients are incorporated into the rubber. This ensures a complete and uniform distribution of the components in the rubber. It is important to keep the temperature as low as possible during the mixing process. Components not included in this step constitute a curing system. These are usually added in the last step, usually at a lower temperature.

  An example of a typical mixing process is as follows. This is for a two-stage mixing of Kevlar® pulp (Kevlar® Engineered Elastomer (Kevlar® EE)) dispersed in an elastomer into a neoprene-type rubber.

First Stage Half of the neoprene, then Kevlar® EE, and finally the remaining neoprene and magnesium oxide are added sequentially with mixing. Mix effectively for 1-1.5 minutes. Add loose fibers (if any). Mix for at least 30 seconds. Add fillers, plasticizers, antioxidants and other additives. Increase the mixer speed as necessary to achieve the desired temperature and continue mixing until a good dispersion of the fibers is obtained. The first stage formulation is dispensed and cooled at a dumping temperature not exceeding 105-110 ° C.

Second Stage Sequentially add half of the cooled first stage followed by zinc oxide, hardener and the remainder of the first pass mixture. Empty in a dispensing roll at 100-105 ° C.

  More information about elastomer formulations can be found in The Vanderbilt Rubber Handbook, Thirteenth Edition, published by R.C. T. T. et al. Vanderbilt Company Inc. , Norwalk, CT, pages 496-507, and US Pat. Nos. 5,331,053; 5,391,623; 5,480,941 and 5, 830,395.

  Under some circumstances, mixing of the ingredients can also be accomplished by roll milling. Fiber alignment is achieved during the rolling and / or dispensing process performed under heat and pressure. A calender is a set of multiple large diameter rolls that squeeze a rubber compound into thin sheets.

  Another approach is to use an extrusion process where the ingredients are mixed and extruded into sheets in a single process. The extruder consists of a screw and barrel, a screw drive, a heater and a die. The extruder applies heat and pressure to the blend. By proper selection of the extrusion die channel design and geometry, the fibers are aligned in the X, Y, or Z direction in the extrudate, corresponding to the circumferential, meridian and radial directions in the overlay, respectively. Can be. In a tapered die, the channel thickness decreases towards the die exit, so that the fibers are aligned in the machine direction (circumferential direction in the plane of the extruded sheet). Inserting the baffle into the die assembly will result in fibers that are aligned laterally (in the meridian direction) in the plane of the extruded sheet. A die design in which the thickness of the channel opening increases towards the exit face of the die will give a fiber orientation (radial) perpendicular to the plane of the extruded sheet. For tire treads, the die cross-sectional profile is tailored to the desired tread design and the tread can be extruded as a single piece. In such a tread, all fibers are aligned in the direction governed by the selected die. If different fiber orientations are desired at different portions or areas across the tread, then multiple die heads are required, and each die is selected to provide the desired fiber orientation suitable for that area.

  There are three major stages in tire manufacturing: component assembly, pressing, and curing. In component assembly, a drum or cylinder is used as a tool on which various components are placed. During assembly, the various components are spliced or glued together. A typical sequence for laying up tire components is to first position the rubber sheet inner liner. Such liners are formulated with additives that result in low air permeability. Thereby, it becomes possible to seal the air in a tire. The second component is a layer of rolled body ply fabric or cord coated with rubber and adhesion promoter. One or more body plies are folded down on the drum. A steel bead is applied and the liner ply is folded back, thereby wrapping the bead. The bead rubber includes additives to maximize strength and toughness. Next, the apex is positioned. Apex is a triangular extruded profile that meshes with the bead to provide a cushion between the rigid bead and the soft inner liner and body ply assembly. This is followed by a pair of chafer strips and sidewalls. These are resistant to wear when the tire is mounted on the rim. The drum is then shrunk and the first stage assembly is ready for the second component assembly stage.

  The second stage of assembly takes place on an inflatable bladder mounted on a steel ring. An unvulcanized first stage assembly is mounted on the ring and a bladder expands it to the belt guide assembly. Next, a steel belt for imparting puncture resistance is installed at a predetermined position. The belt is a rolled sheet consisting of a rubber layer, a closely spaced steel cord layer, and a second rubber layer. The steel cords are oriented radially in radial tire configurations and at opposing angles in bias tire configurations. Passenger car tires are usually made using two or three belts. The overlay is applied over the top belt. For the composite overlay described herein, the short fiber elastomer strip component and the continuous filament cord component containing oriented fibers are positioned at a desired location, for example as shown in FIGS. A technique for aligning fibers in an elastomer is a method of generating shear conditions during the mixing / compounding process. Such methods include kneading, rolling, injection molding and extrusion. Examples of these techniques are US Pat. Nos. 6,106,752 (injection molding); 6,899,782 (extrusion) and 7,005,022 (extrusion and Can be found in needling.

  Next, the tread rubber profile of the sub-tread layer and the tread block layer, which are the final components, is applied. The tread assembly is rollered to integrate it into the belt, and then the finished assembly (green cover) is removed from the machine. Many higher performance tires include an optional extruded cushion component between the belt package and the tread to isolate the tread from mechanical wear by the steel belt. If desired, the tire building process can be automated, with each component applied separately along a number of assembly points. Following layup, the assembly is pressed to integrate all components into a shape that is very close to the final tire dimensions.

Curing or vulcanization of the elastomer to the final tire shape takes place in a hot mold. The mold is engraved with a tire tread pattern. The unvulcanized tire assembly is placed on the lower mold bead sheet, the mold is closed while the rubber bladder is inserted into the unvulcanized tire and the bladder expands to a pressure of about 25 kgf / cm ^2. Yes. As a result, the unvulcanized tire flows into the mold and assumes a tread pattern. The bladder is filled with a recirculating heat transfer medium (eg, steam, hot water or an inert gas). Cure temperatures and cure times will vary for different tire types and elastomer formulations, but typical values are cure temperatures of about 150-180 degrees Celsius and cure times of about 12-25 minutes. . For large tires, the cure time can be much longer. At the end of curing, the pressure is completely released, the mold is opened, and the tire is removed from the mold. The tire can be placed on a post-cure inflator that keeps the tire fully inflated while the tire cools.

  The invention is illustrated by the following examples. The following examples are designed to be illustrative and are not intended to be limiting in nature. In the following examples, all parts, proportions and percentages are by weight unless otherwise indicated.

  Specimens that were identical in both composition and dimensions were used to represent overlay compositions and structures. In conventional tire configurations, different compositions can be used for this component part.

  Rubber formulations similar to those described above were used in all examples. With this rubber, a sheet was formed by kneading and rolling.

Comparative Example A
In this example, a rubber sheet containing nylon 66 continuous filament cord at 32 warps per inch (approximately 13 warps per cm) was incorporated into a compounded rubber strip. The strip was placed on a cylinder-forming rubber composite that mimics a tire with inner liner, carcass and belt components in place. These components were assembled on a mandrel and the rubber was cured under heat and pressure to obtain a cured rubber cylinder representative of the tire.

Example 1
Example 1 simulates a tire overlay including the nylon cord of Comparative Example A on the shoulder and an aramid short fiber (Kevlar EE (registered trademark)) in the center.

  The Kevlar EE® used was Merge 1F722 commercially available from DuPont, which was used at a level of 3 parts per 100 parts rubber. The rubber composition was the same as for Comparative Example A. This fiber was incorporated into a rubber compound by a method similar to that described for two pass mixing in the Kevlar® Engineered Elastomer Processing Guide. This formulation containing the fibers was then kneaded to align the fibers, thereby forming a sheet. Two second sheet strips of Comparative Example A (one strip at each end) were placed on a cylindrical mold mandrel. A first strip containing the compounded Kevlar EE® elastomer was placed around the central portion of the mandrel. The rubber was then cured under heat and pressure to yield a cured rubber cylinder having an inner diameter of 5.25 inches (133.3 mm) and a thickness of 0.1875 inches (4.76 mm). The fibers in Kevlar® EE were aligned in the hoop direction.

Example 2
Example 2 simulates a tire overlay in which the entire overlay includes aramid short fibers and rubber. The Kevlar EE® elastomer and rubber material were the same as for Example 1.

  The above test of the sample to simulate the noise emanating from the tire will demonstrate significant noise reduction with the design of Examples 1 and 2 when compared to the design of Comparative Example A.

Claims (14)

A tire including an overlay ply,
(I) The shoulder portion of the overlay includes an elastomer and a polymer or non-polymer reinforcing short fiber present in an amount of 0.1 to 10 parts of fiber per 100 parts of elastomer, wherein the reinforcing short fiber is 1 dtex. Having a tenacity of at least 2 grams per d, a modulus of at least 10 grams per dtex and a length of 0.1-8 mm, and the fibers are aligned substantially parallel to each other at a controlled orientation angle in the overlay And the orientation is selected such that it will reduce tire noise, and (ii) the portion of the overlay in the crown of the tire is a cord of continuous filament polymer fibers or continuous metal strands or combinations thereof The cord is circumferential around the tire Are aligned to,
tire.   The overlay of claim 1, wherein the reinforcing short fibers are present in an orientation selected from the group consisting of circumferential, meridian, radial, and combinations thereof.   The reinforcing short fibers are circumferentially oriented reinforcing short fibers in at least one XY or XZ layer, at least one meridian oriented reinforcing short fibers in at least one XY or YZ layer, and at least one The overlay ply of claim 2, selected from the group consisting of the reinforcing short fibers in a radial orientation in an XZ or YZ layer. A tire including an overlay,
(I) the overlay in the crown portion of the tire comprises an elastomer and short fibers for reinforcement of polymer or non-polymer present in an amount of 0.1 to 10 parts of fiber per 100 parts of elastomer; The fibers have a tenacity of at least 2 grams per dtex, a modulus of at least 10 grams per dtex, and a length of 0.1-8 mm, and the fibers are substantially one another with a controlled orientation angle in the overlay. Aligned in parallel, the orientation is selected so that it will reduce tire noise, and (ii) the shoulder portion of the overlay of the tire is a continuous filament polymer fiber or a continuous metal strand or their A cord of the combination, wherein the cord is the tire Are aligned circumferentially around,
tire.   The overlay of claim 4, wherein the reinforcing short fibers are present in an orientation selected from the group consisting of circumferential, meridian, radial, and combinations thereof.   The reinforcing short fibers are present in at least one XY or XZ layer in which the reinforcing short fibers are present in a circumferential orientation, and the reinforcing short fibers in at least one XY or YZ layer are present in a meridian orientation 6. The overlay ply of claim 5, wherein the overlay ply is selected from the group of: and wherein the reinforcing short fibers in at least one XZ or YZ layer are present in a radial orientation. A tire comprising an overlay ply free of continuous filament polymer fibers or continuous metal strands, wherein the overlay is present in an amount of 0.1 to 10 parts of fiber per 100 parts of elastomer and elastomer. Short fibers having a tenacity of at least 2 grams per dtex, a modulus of at least 10 grams per dtex and a length of 0.1-8 mm, and the fibers were controlled in an overlay Aligned substantially parallel to each other at an orientation angle, the orientation being selected such that it will reduce tire noise;
tire.   The overlay of claim 7, wherein the reinforcing short fibers are present in an orientation selected from the group consisting of circumferential, meridian, radial, and combinations thereof.   The reinforcing short fibers are circumferentially oriented reinforcing short fibers in at least one XY or XZ layer, at least one meridian oriented reinforcing short fibers in at least one XY or YZ layer, and at least one 9. The overlay ply of claim 8, wherein the overlay ply is selected from the group consisting of the reinforcing short fibers in a radial orientation in an XZ or YZ layer. A method for reducing noise caused by a tire shoulder,
(A) identifying the mechanism causing the noise;
(B) supplying an elastomer compound for tire overlay;
(C) introducing into the elastomer blend a polymer or non-polymer reinforcing short fiber having an orientation adapted to reduce tire noise based on the mechanism identified in step (a); Including a method.   11. The noise reduction of claim 10, further comprising the step (d) of introducing a cord comprising continuous reinforcing fibers disposed adjacent to the shoulder blend of step (c) in the crown of the tire overlay. Method. A method for reducing noise caused by a tire shoulder,
(A) identifying the mechanism causing the noise;
(B) supplying an elastomer compound for the crown of the tire overlay;
(C) introducing into the elastomer blend a polymer or non-polymer reinforcing short fiber having an orientation adapted to reduce tire noise based on the mechanism identified in step (a); ,
(D) introducing a cord comprising continuous reinforcing fibers disposed adjacent to the crown formulation of step (c) into a shoulder of the tire overlay. A method for manufacturing a tire including a composite overlay, the composite overlay further comprising:
Comprising 0.1 to 10 parts of polymer or non-polymer short fibers per 100 parts by weight of the elastomer, the fibers being 0.1 to 8 mm long, at least 6 grams tenacity per dtex and at least 10 per dtex Characterized as having a gram modulus, the majority of the fibers being substantially oriented in a plane substantially parallel to or perpendicular to the circumference of the tire;
The method
(A) blending an uncured elastomer comprising polymer or non-polymer short fibers, elastomer and other additives in a high shear mixer, kneading roll machine or extruder;
(B) rolling or extruding the uncured elastomer into one or more layers or sheets in which the fibers are aligned in a desired direction;
(C) sequentially assembling the first stage components of the tire assembly on the drum;
(D) sequentially assembling a second stage component of the tire assembly on a bladder press tool, comprising the step (b) being placed on a shoulder portion of an overlay;
(E) placing the tire assembly in a mold and curing the elastomer blend by heat and pressure. A method for manufacturing a tire including a composite overlay, the composite overlay further comprising:
Comprising 0.1 to 8 parts polymer or non-polymer short fiber per 100 parts by weight of the elastomer, the fiber being 0.1 to 8 mm long, at least 6 grams tenacity per dtex and at least 10 per dtex Characterized as having a gram modulus, the majority of the fibers being substantially oriented in a plane substantially parallel to or perpendicular to the circumference of the tire;
The method
(A) blending an uncured elastomer containing short fibers, elastomer and other additives in a high shear mixer, kneading roll machine or extruder;
(B) rolling or extruding the uncured elastomer into one or more layers or sheets in which the fibers are aligned in a desired direction;
(C) sequentially assembling the first stage components of the tire assembly on the drum;
(D) sequentially assembling a second stage component of the tire assembly on a bladder press tool, the process comprising installing the sheet of step (b) on a crown portion of an overlay;
(E) placing the tire assembly in a mold and curing the elastomer blend by heat and pressure.

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